This invention relates to a light duty liquid cleaning composition having an improved preservative system and the composition imparts mildness to the skin and is designed in particular for cleaning hard surfaces as well as being effective in removing grease soil and/or bath soil and in leaving unrinsed surfaces with a shiny appearance.
In recent years all-purpose liquid detergents have become widely accepted for cleaning hard surfaces, e.g., painted woodwork and panels, tiled walls, wash bowls, bathtubs, linoleum or tile floors, washable wall paper, etc. Such all-purpose liquids comprise clear and opaque aqueous mixtures of water-soluble organic detergents and water-soluble detergent builder salts. In order to achieve comparable cleaning efficiency with granular or powdered all-purpose cleaning compositions, use of water-soluble inorganic phosphate builder salts was favored in the prior art all-purpose liquids. For example, such early phosphate-containing compositions are described in U.S. Pat. Nos. 2,560,839; 3,234,138; 3,350,319; and British Pat. No. 1,223,739.
In view of the environmentalist""s efforts to reduce phosphate levels in ground water, improved all-purpose liquids containing reduced concentrations of inorganic phosphate builder salts or non-phosphate builder salts have appeared. A particularly useful self-opacified liquid of the latter type is described in U.S. Pat. No. 4,244,840.
However, these prior art all-purpose liquid detergents containing detergent builder salts or other equivalent tend to leave films, spots or streaks on cleaned unrinsed surfaces, particularly shiny surfaces. Thus, such liquids require thorough rinsing of the cleaned surfaces which is a time-consuming chore for the user.
In order to overcome the foregoing disadvantage of the prior art all-purpose liquid, U.S. Pat. No. 4,017,409 teaches that a mixture of paraffin sulfonate and a reduced concentration of inorganic phosphate builder salt should be employed. However, such compositions are not completely acceptable from an environmental point of view based upon the phosphate content. On the other hand, another alternative to achieving phosphate-free all-purpose liquids has been to use a major proportion of a mixture of anionic and nonionic detergents with minor amounts of glycol ether solvent and organic amine as shown in U.S. Pat. No. 3,935,130. Again, this approach has not been completely satisfactory and the high levels of organic detergents necessary to achieve cleaning cause foaming which, in turn, leads to the need for thorough rinsing which has been found to be undesirable to today""s consumers.
Another approach to formulating hard surface or all-purpose liquid detergent composition where product homogeneity and clarity are important considerations involves the formation of oil-in-water (o/w) microemulsions which contain one or more surface-active detergent compounds, a water-immiscible solvent (typically a hydrocarbon solvent), water and a xe2x80x9ccosurfactantxe2x80x9d compound which provides product stability. By definition, an o/w microemulsion is a spontaneously forming colloidal dispersion of xe2x80x9coilxe2x80x9d phase particles having a particle size in the range of about 25 to about 800 xc3x85 in a continuous aqueous phase.
In view of the extremely fine particle size of the dispersed oil phase particles, microemulsions are transparent to light and are clear and usually highly stable against phase separation.
Patent disclosures relating to use of grease-removal solvents in o/w microemulsions include, for example, European Patent Applications EP 0137615 and EP 0137616xe2x80x94Herbots et al; European Patent Application EP 0160762xe2x80x94Johnston et al; and U.S. Pat. No. 4,561,991xe2x80x94Herbots et al. Each of these patent disclosures also teaches using at least 5% by weight of grease-removal solvent.
It also is known from British Patent Application GB 2144763A to Herbots et al, published Mar. 13, 1985, that magnesium salts enhance grease-removal performance of organic grease-removal solvents, such as the terpenes, in o/w microemulsion liquid detergent compositions. The compositions of this invention described by Herbots et al. require at least 5% of the mixture of grease-removal solvent and magnesium salt and preferably at least 5% of solvent (which may be a mixture of water-immiscible non-polar solvent with a sparingly soluble slightly polar solvent) and at least 0.1% magnesium salt.
However, since the amount of water immiscible and sparingly soluble components which can be present in an o/w microemulsion, with low total active ingredients without impairing the stability of the microemulsion is rather limited (for example, up to about 18% by weight of the aqueous phase), the presence of such high quantities of grease-removal solvent tend to reduce the total amount of greasy or oily soils which can be taken up by and into the microemulsion without causing phase separation.
The following representative prior art patents also relate to liquid detergent cleaning compositions in the form of o/w microemulsions: U.S. Pat. Nos. 4,472,291xe2x80x94Rosario; 4,540,448xe2x80x94Gauteer et al; 3,723,330xe2x80x94Sheflin; etc.
Liquid detergent compositions which include terpenes, such as d-limonene, or other grease-removal solvent, although not disclosed to be in the form of o/w microemulsions, are the subject matter of the following representative patent documents: European Patent Application 0080749; British Patent Specification 1,603,047; 4,414,128; and 4,540,505. For example, U.S. Pat. No. 4,414,128 broadly discloses an aqueous liquid detergent composition characterized by, by weight:
(a) from about 1% to about 20% of a synthetic anionic, nonionic, amphoteric or zwitterionic surfactant or mixture thereof;
(b) from about 0.5% to about 10% of a mono- or sesquiterpene or mixture thereof, at a weight ratio of (a):(b) lying in the range of 5:1 to 1:3; and
(c ) from about 0.5% about 10% of a polar solvent having a solubility in water at 15xc2x0 C. in the range of from about 0.2% to about 10%. Other ingredients present in the formulations disclosed in this patent include from about 0.05% to about 2% by weight of an alkali metal, ammonium or alkanolammonium soap of a C13-C24 fatty acid; a calcium sequestrant from about 0.5% to about 13% by weight; non-aqueous solvent, e.g., alcohols and glycol ethers, up to about 10% by weight; and hydrotropes, e.g., urea, ethanolamines, salts of lower alkylaryl sulfonates, up to about 10% by weight. All of the formulations shown in the Examples of this patent include relatively large amounts of detergent builder salts which are detrimental to surface shine.
U.S. Pat. 5,082,584 discloses a microemulsion composition having an anionic surfactant, a cosurfactant, nonionic surfactant, perfume and water; however, these compositions are not light duty liquid compositions.
The present invention relates to a light duty liquid detergent compositions with high foaming properties, containing a nonionic surfactant, a sulfonate surfactant, an ethoxylated alkyl ether sulfate surfactant, an inorganic magnesium salt, polyethylene glycol, an improved preservative system and water. The compositions may also optionally contain from 0 to 10% of an alkyl monoalkanol amide, an alkyl dialkanol amide, an amine oxide, a zwitterionic surfactant and/or alkyl polyglucoside surfactant.
Nonionic surfactants are in general chemically inert and stable toward pH change and are therefore well suited for mixing and formulation with other materials. The superior performance of nonionic surfactants on the removal of oily soil is well recognized. Nonionic surfactants are also known to be mild to human skin. However, as a class, nonionic surfactants are known to be low or moderate foamers. Consequently, for detergents which require copious and stable foam, the application of nonionic surfactants is limited. There have been substantial interest and efforts to develop a high foaming detergent with nonionic surfactants as the major active ingredient. Yet, little has been achieved.
The prior art is replete with light duty liquid detergent compositions containing nonionic surfactants in combination with anionic and/or betaine surfactants wherein the nonionic detergent is not the major active surfactant, as shown in U.S. Pat. No. 3,658,985 wherein an anionic based shampoo contains a minor amount of a fatty acid alkanolamide. U.S. Pat. No. 3,769,398 discloses a betaine-based shampoo containing minor amounts of nonionic surfactants. This patent states that the low foaming properties of nonionic detergents renders its use in shampoo compositions non-preferred. U.S. Pat. No. 4,329,335 also discloses a shampoo containing a betaine surfactant as the major ingredient and minor amounts of a nonionic surfactant and of a fatty acid mono- or di-ethanolamide. U.S. Pat. No. 4,259,204 discloses a shampoo comprising 0.8-20% by weight of an anionic phosphoric acid ester and one additional surfactant which may be either anionic, amphoteric, or nonionic. U.S. Pat. No. 4,329,334 discloses an anionic-amphoteric based shampoo containing a major amount of anionic surfactant and lesser amounts of a betaine and nonionic surfactants.
U.S. Pat. No. 3,935,129 discloses a liquid cleaning composition based on the alkali metal silicate content and containing five basic ingredients, namely, urea, glycerin, triethanolamine, an anionic detergent and a nonionic detergent. The silicate content determines the amount of anionic and/or nonionic detergent in the liquid cleaning composition. However, the foaming property of these detergent compositions is not discussed therein.
U.S. Pat. No. 4,129,515 discloses a heavy duty liquid detergent for laundering fabrics comprising a mixture of substantially equal amounts of anionic and nonionic surfactants, alkanolamines and magnesium salts, and, optionally, zwitterionic surfactants as suds modifiers.
U.S. Pat. No. 4,224,195 discloses an aqueous detergent composition for laundering socks or stockings comprising a specific group of nonionic detergents, namely, an ethylene oxide of a secondary alcohol, a specific group of anionic detergents, namely, a sulfuric ester salt of an ethylene oxide adduct of a secondary alcohol, and an amphoteric surfactant which may be a betaine, wherein either the anionic or nonionic surfactant may be the major ingredient.
The prior art also discloses detergent compositions containing all nonionic surfactants as shown in U.S. Pat. Nos. 4,154,706 and 4,329,336 wherein the shampoo compositions contain a plurality of particular nonionic surfactants in order to effect desirable foaming and detersive properties despite the fact that nonionic surfactants are usually deficient in such properties.
U.S. Pat. No. 4,013,787 discloses a piperazine based polymer in conditioning and shampoo compositions which may contain all nonionic surfactant or all anionic surfactant.
U.S. Pat. 4,671,895 teaches a liquid detergent composition containing an alcohol sulfate surfactant, a nonionic surfactant, a paraffin sulfonate surfactant, an alkyl ether sulfate surfactant and water but fails to disclose an alkyl polysaccharide surfactant.
U.S. Pat. No. 4,450,091 discloses high viscosity shampoo compositions containing a blend of an amphoteric betaine surfactant, a polyoxybutylene polyoxyethylene nonionic detergent, an anionic surfactant, a fatty acid alkanolamide and a polyoxyalkylene glycol fatty ester. But, none of the exemplified compositions contains an active ingredient mixture wherein the nonionic detergent is present in major proportion, probably due to the low foaming properties of the polyoxybutylene polyoxyethylene nonionic detergent.
U.S. Pat. No. 4,595,526 describes a composition comprising a nonionic surfactant, a betaine surfactant, an anionic surfactant and a C12-C14 fatty acid monethanolamide foam stabilizer.
However, none of the above-cited patents discloses a liquid detergent composition containing a nonionic surfactant, an anionic sulfonate surfactant, an ethoxylated alkyl ether sulfate surfactant, an improved preservative system, an inorganic magnesium salt, polyethylene glycol and water and optionally an alkyl monoalkanol amide such as an alkanol monoethanol amide (LMMEA), a zwitterionic surfactant, an amine oxide and/or an alkyl polyglucoside surfactant, and the composition does not contain gluconic acid, ethylene diamine tetraacetate sodium salt, isothiazolones, 1,3-dimethylol-5,5-dimethylhydantoin, 5-bromo-5-nitro-1,3dioxane, any abrasives, silicas, alkaline earth metal carbonates, alkyl glycine surfactant, cyclic imidinium surfactant, alkali metal carbonates or more than 3 wt. % of a fatty acid or its salt thereof, a nitrogenous buffer selected from the group consisting of ammonium or alkaline carbonates, quanidine derivatives, alkoxyl alkylamines, and alkyleneamines, and a grease release agent which is an ethoxylated maleic anhydride-alpha-olefin copolymer having a comblike structure with both hydrophobic and hydrophilic chains and the copolymer is characterized by the formula: 
wherein n is about 5 to about 14, x is about 7 to 19, and y is of such a value as to provide a molecular weight about 10,000 to about 30,000.
This invention relates to a light duty liquid detergent composition containing a nonionic surfactant, a sulfate or sulfonate anionic surfactant, and an ethoxylated alkyl ether sulfate surfactant, a preservative system, polyethylene glycol, an inorganic magnesium salt and water and optionally an alkyl monoalkanol amide, a zwitterionic surfactant, an amine oxide and/or an alkyl polyglucoside surfactant, wherein the composition does not contain gluconic acid, ethylene diamine tetraacetate sodium salt, isothiazolones, 1,3-dimethylol-5,5-dimethylhydantoin, 5-bromo-5-nitro-1,3dioxane, any silicas, abrasives, alkali metal carbonates, alkaline earth metal carbonates, alkyl glycine surfactant, cyclic imidinium surfactant, or more than 3 wt. % of a fatty acid or salt thereof.
An object of this invention is to provide a novel light duty liquid detergent with desirable high foaming and cleaning properties which is mild to the human skin and has an improved preservative system.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the foregoing and other objects and in accordance with the purpose of the present invention, as embodied and broadly described herein the novel, high foaming light duty liquid detergent of this invention comprises a water soluble, ethoxylated nonionic surfactant, polyethylene glycol, an ethoxylated alkyl ether sulfate surfactant, a sulfate or sulfonate anionic surfactant, an improved preservative system, an inorganic magnesium salt and water and optionally an alkyl monoalkanol amide, amine oxide, zwitterionic surfactant and/or alkyl polyglucoside surfactant, wherein the composition does not contain gluconic acid, ethylene diamine tetraacetate sodium salt, 5-bromo-5-nitro-1,3dioxane, isothiazolones, imino dissucinate-sodium salt, any silicas, abrasives, alkali metal carbonates, alkaline earth metal carbonates, alkyl glycine surfactant, cyclic imidinium surfactant or more than 3 wt. % of a fatty acid or salt thereof, a nitrogenous buffer selected from the group consisting of ammonium or alkaline carbonates, quanidine derivatives, alkoxyl alkylamines, and alkyleneamines, and a grease release agent which is an ethoxylated maleic anhydride-alpha-olefin copolymer having a comblike structure with both hydrophobic and hydrophilic chains and the copolymer is characterized by the formula: 
wherein n is about 5 to about 14, x is about 7 to 19, and y is of such a value as to provide a molecular weight about 10,000 to about 30,000.
The light duty liquid compositions of the instant invention comprise approximately by weight:
(a) 10% to 30% of an alkali metal salt of an anionic sulfonate surfactant;
(b) 2% to 10% of an alkali metal salt of a C8-18 ethoxylated alkyl ether sulfate;
(c) 0.1% to 6% of polyethylene glycol;
(d) 1% to 14% of a nonionic surfactant;
(e) 0 to 10%, more preferably 0.1% to 8% of at least one solubilizing agent;
(f) 0.1% to 5% of an inorganic magnesium compound;
(g) 0.001% to 0.4% of a preservative which is 2-bromo-2-nitropropane-1,3-diol (Bronopol);
(h) 0.01% to 0.3% of a preservative potentiator which is preferably a trialkali metal salt of ethylene diamine N-Nxe2x80x2-disuccinate (EDDS) such as the sodium salt; and
(i) the balance being water.
The instant compositions do not contain any grease release agents such as choline chloride or buffering system which is a nitrogenous buffer which is ammonium or alkaline earth carbonate, guanidine derivates, alkoxylalkyl amines and alkyleneamines and the composition is pourable and not a gel and the compositions exhibit a viscosity in the range of 100 to 1000 milli Pascal.second (m Pas) as measured at 25xc2x0 C. with a Brookfield RVT viscometer.
The nonionic surfactant is present in amounts of about 1 to 14%, preferably 2% to 12% by weight of the composition and provides superior performance in the removal of oily soil and mildness to human skin.
The water soluble nonionic surfactants utilized in this invention are commercially well known and include the primary aliphatic alcohol ethoxylates, secondary aliphatic alcohol ethoxylates, alkylphenol ethoxylates and ethylene-oxide-propylene oxide condensates on primary alkanols, such a Plurafacs (BASF) and condensates of ethylene oxide with sorbitan fatty acid esters such as the Tweens (ICI). The nonionic synthetic organic detergents generally are the condensation products of an organic aliphatic or alkyl aromatic hydrophobic compound and hydrophilic ethylene oxide groups. Practically any hydrophobic compound having a carboxy, hydroxy, amido, or amino group with a free hydrogen attached to the nitrogen or the oxygen can be condensed with ethylene oxide or with the polyhydration product thereof, polyethylene glycol, to form a water-soluble nonionic detergent. Further, the length of the polyethenoxy chain can be adjusted to achieve the desired balance between the hydrophobic and hydrophilic elements.
The nonionic detergent class includes the condensation products of a higher alcohol (e.g., an alkanol containing about 8 to 18 carbon atoms in a straight or branched chain configuration) condensed with about 5 to 30 moles of ethylene oxide, for example, lauryl or myristyl alcohol condensed with about 16 moles of ethylene oxide (EO), tridecanol condensed with about 6 to moles of EO, myristyl alcohol condensed with about 10 moles of EO per mole of myristyl alcohol, the condensation product of EO with a cut of coconut fatty alcohol containing a mixture of fatty alcohols with alkyl chains varying from 10 to about 14 carbon atoms in length and wherein the condensate contains either about 6 moles of EO per mole of total alcohol or about 9 moles of EO per mole of alcohol and tallow alcohol ethoxylates containing 6 EO to 11 EO per mole of alcohol.
A preferred group of the foregoing nonionic surfactants are the Neodol ethoxylates (Shell Co.), which are higher aliphatic, primary alcohol containing about 9-15 carbon atoms, such as C9-C11 alkanol condensed with 7 to 10 moles of ethylene oxide (Neodol 91-8), C12-13 alkanol condensed with 6.5 moles ethylene oxide (Neodol 23-6.5), C12-15 alkanol condensed with 12 moles ethylene oxide (Neodol 25-12), C14-15 alkanol condensed with 13 moles ethylene oxide (Neodol 45-13), and the like. Such ethoxamers have an HLB (hydrophobic lipophilic balance) value of about 8 to 15 and give good O/W emulsification, whereas ethoxamers with HLB values below 8 contain less than 5 ethyleneoxide groups and tend to be poor emulsifiers and poor detergents.
Additional satisfactory water soluble alcohol ethylene oxide condensates are the condensation products of a secondary aliphatic alcohol containing 8 to 18 carbon atoms in a straight or branched chain configuration condensed with 5 to 30 moles of ethylene oxide. Examples of commercially available nonionic detergents of the foregoing type are C11-C15 secondary alkanol condensed with either 9 EO (Tergitol 15-S-9) or 12 EO (Tergitol 15-S-12) marketed by Union Carbide.
Other suitable nonionic detergents include the polyethylene oxide condensates of one mole of alkyl phenol containing from about 8 to 18 carbon atoms in a straight- or branched chain alkyl group with about 5 to 30 moles of ethylene oxide. Specific examples of alkyl phenol ethoxylates include nonyl phenol condensed with about 9.5 moles of EO per mole of nonyl phenol, dinonyl phenol condensed with about 12 moles of EO per mole of phenol, dinonyl phenol condensed with about 15 moles of EO per mole of phenol and di-isoctylphenol condensed with about 15 moles of EO per mole of phenol. Commercially available nonionic surfactants of this type include Igepal CO-630 (nonyl phenol ethoxylate) marketed by GAF Corporation.
Also among the satisfactory nonionic detergents are the water-soluble condensation products of a C8-C20 alkanol with a heteric mixture of ethylene oxide and propylene oxide wherein the weight ratio of ethylene oxide to propylene oxide is from 2.5:1 to 4:1, preferably 2.8:1 to 3.3:1, with the total of the ethylene oxide and propylene oxide (including the terminal ethanol or propanol group) being from 60-85%, preferably 70-80%, by weight. Such detergents are commercially available from BASF-Wyandotte and a particularly preferred detergent is a C10-C16 alkanol condensate with ethylene oxide and propylene oxide, the weight ratio of ethylene oxide to propylene oxide being 3:1 and the total alkoxy content being about 75% by weight.
Condensates of 2 to 30 moles of ethylene oxide with sorbitan mono- and tri-C10-C20 alkanoic acid esters having a HLB of 8 to 15 also may be employed as the nonionic detergent ingredient in the described composition. These surfactants are well known and are available from Imperial Chemical Industries under the Tween trade name. Suitable surfactants include polyoxyethylene (4) sorbitan monolaurate, polyoxyethylene (4) sorbitan monostearate, polyoxyethylene (20) sorbitan trioleate and polyoxyethylene (20) sorbitan tristearate.
Other suitable water-soluble nonionic detergents are marketed under the trade name xe2x80x9cPluronics.xe2x80x9d The compounds are formed by condensing ethylene oxide with a hydrophobic base formed by the condensation of propylene oxide with propylene glycol. The molecular weight of the hydrophobic portion of the molecule is of the order of 950 to 4000 and preferably 200 to 2,500. The addition of polyoxyethylene radicals to the hydrophobic portion tends to increase the solubility of the molecule as a whole so as to make the surfactant water-soluble. The molecular weight of the block polymers varies from 1,000 to 15,000 and the polyethylene oxide content may comprise 20% to 80% by weight. Preferably, these surfactants will be in liquid form and satisfactory surfactants are available as grades L 62 and L 64.
The anionic sulfonate surfactants which may be used in the detergent of this invention are water soluble and include the sodium, potassium, ammonium and ethanolammonium salts of linear C8-C16 alkyl benzene sulfonates; C10-C20 paraffin sulfonates, alpha olefin sulfonates containing about 10-24 carbon atoms and C8-C18 alkyl sulfates and mixtures thereof. The preferred anionic sulfonate surfactant is a C12-18 paraffin sulfonate.
The paraffin sulfonates may be monosulfonates or di-sulfonates and usually are mixtures thereof, obtained by sulfonating paraffins of 10 to 20 carbon atoms. Preferred paraffin sulfonates are those of C12-18 carbon atoms chains, and more preferably they are of C14-17 chains. Paraffin sulfonates that have the sulfonate group(s) distributed along the paraffin chain are described in U.S. Pat. Nos. 2,503,280; 2,507,088; 3,260,744; and 3,372,188; and also in German Pat. 735,096. Such compounds may be made to specifications and desirably the content of paraffin sulfonates outside the C14-17 range will be minor and will be minimized, as will be any contents of di- or poly-sulfonates.
Examples of suitable other sulfonated anionic detergents are the well known higher alkyl mononuclear aromatic sulfonates, such as the higher alkylbenzene sulfonates containing 9 to 18 or preferably 9 to 16 carbon atoms in the higher alkyl group in a straight or branched chain, or C8-15 alkyl toluene sulfonates. A preferred alkylbenzene sulfonate is a linear alkylbenzene sulfonate having a higher content of 3-phenyl (or higher) isomers and a correspondingly lower content (well below 50%) of 2-phenyl (or lower) isomers, such as those sulfonates wherein the benzene ring is attached mostly at the 3 or higher (for example 4, 5, 6 or 7) position of the alkyl group and the content of the isomers in which the benzene ring is attached in the 2 or 1 position is correspondingly low. Preferred materials are set forth in U.S. Pat. No. 3,320,174, especially those in which the alkyls are of 10 to 13 carbon atoms.
The C8-18 ethoxylated alkyl ether sulfate surfactants have the structure
Rxe2x80x94(OCHCH2)nOSOxe2x88x923M+
wherein n is about 1 to about 22 more preferably 1 to 3 and R is an alkyl group having about 8 to about 18 carbon atoms, more preferably 12 to 15 and natural cuts, for example, C12-14 or C12-16 and M is an ammonium cation or a metal cation, most preferably sodium. The ethoxylated alkyl ether sulfate is present in the composition at a concentration of about 2.0 to about 5.0 wt. %, more preferably about 2.5% to 4.5 wt.
The ethoxylated alkyl ether sulfate may be made by sulfating the condensation product of ethylene oxide and C8-10 alkanol, and neutralizing the resultant product. The ethoxylated alkyl ether sulfates differ from one another in the number of carbon atoms in the alcohols and in the number of moles of ethylene oxide reacted with one mole of such alcohol. Preferred ethoxylated alkyl ether polyethenoxy sulfates contain 12 to 15 carbon atoms in the alcohols and in the alkyl groups thereof, e.g., sodium myristyl (3 EO) sulfate.
The composition also contains an inorganic or organic salt of oxide of a multivalent metal cation, particularly Mg++. The metal salt or oxide provides several benefits including improved cleaning performance in dilute usage, particularly in soft water. Magnesium sulfate, either anhydrous or hydrated (e.g., heptahydrate), is especially preferred as the magnesium salt. Good results also have been obtained with magnesium oxide, magnesium chloride, magnesium acetate, magnesium propionate and magnesium hydroxide. These magnesium salts can be used with formulations at neutral or acidic pH since magnesium hydroxide will not precipitate at these pH levels.
Although magnesium is the preferred multivalent metal from which the salts (inclusive of the oxide and hydroxide) are formed, other polyvalent metal ions also can be used provided that their salts are nontoxic and are soluble in the aqueous phase of the system at the desired pH level.
Polyethylene glycol which is used in the instant composition has a molecular weight of 200 to 1,000 wherein the polyethylene glycol has the structure
HO(CH2CH2O)nH
wherein n is 4 to 52. The concentration of the polyethylene glycol in the instant composition is 0.1% to 7 wt. %, more preferably 0.1 wt. % to 5 wt. %.
The instant compositions can contain about 0 to about 10 wt. %, more preferably about 0.1 wt. % to about 8 wt. %, of at least one solubilizing agent which is sodium xylene sulfonate, sodium amine sulfonate, a C2-5 mono, dihydroxy or polyhydroxy alkanols such as ethanol, isopropanol, glycerol ethylene glycol, diethylene glycol and propylene glycol and mixtures thereof. The solubilizing agents are included in order to control low temperature cloud clear properties. Urea can be optionally employed in the instant composition as a supplemental solubilizing agent at a concentration of 0 to about 10 wt. %, more preferably about 0.5 wt. % to about 8 wt. %.
The instant formulas explicitly exclude alkali metal silicates and alkali metal builders such as alkali metal polyphosphates, alkali metal carbonates and alkali metal phosphonates because these materials, if used in the instant composition, would cause the composition to have a high pH as well as leaving residue on the surface being cleaned.
The final essential ingredient in the inventive compositions having improved interfacial tension properties is water. The proportion of water in the microemulsion compositions generally is in the range of 35% to 70%, preferably 40% to 60% by weight of the composition.
The instant composition can optionally contain 0 to 12 wt. %,. more preferably wt. % to 10 wt. % of a surfactant selected from the group consisting of C12-C14 alkyl monoalkanol amides, C12-C14 alkyl dialkanol amine, zwifterionics, amine oxides alkyl polyglucosides and mixtures thereof.
The water-soluble zwitterionic surfactant (betaine), which is optionally used in the light duty liquid detergent composition, provides good foaming properties and mildness. The zwitterionic surfactant is a water soluble betaine having the general formula: 
wherein Xxe2x88x92is selected from the group consisting of SO3xe2x88x92 and CO2xe2x88x92 and R1 is an alkyl group having 10 to about 20 carbon atoms, preferably 12 to 16 carbon atoms, or the amido radical: 
wherein R is an alkyl group having about 9 to 19 carbon atoms and a is the integer 1 to 4; R2 and R3 are each alkyl groups having 1 to 3 carbons and preferably 1 carbon; R4 is an alkylene or hydroxyalkylene group having from 1 to 4 carbon atoms and, optionally, one hydroxyl group. Typical alkyldimethyl betaines include decyl dimethyl betaine or 2-(N-decyl-N, N-dimethylammonia) acetate, coco dimethyl betaine or 2-(N-coco N, N-dimethylammonia) acetate, myristyl dimethyl betaine, palmityl dimethyl betaine, lauryl dimethyl betaine, cetyl dimethyl betaine, stearyl dimethyl betaine, etc. The amidobetaines similarly include cocoamidoethylbetaine, cocoamidopropyl betaine and the like. A preferred betaine is coco (C8-C18) amidopropyl dimethyl betaine.
Amine oxide semi-polar nonionic surfactants comprise cocoamido propyl dimethyl amine oxide and compounds and mixtures of compounds having the formula 
wherein R1 is an alkyl, 2-hydroxyalkyl, 3-hydroxyalkyl, or 3-alkoxy-2-hydroxypropyl radical in which the alkyl and alkoxy, respectively, contain from 8 to 18 carbon atoms, R2 and R3 are each methyl, ethyl, propyl, isopropyl, 2-hydroxyethyl, 2-hydroxypropyl, of 3-hydroxypropyl, and n is from 0 to 10. Particularly preferred are amine oxides of the formula: 
wherein R1 is a C12-16 alkyl and R2 and R3 are methyl or ethyl. The above ethylene oxide condensates, amides, and amine oxides are more fully described in U.S. Pat. No. 4,316,824 which is hereby incorporated herein by reference.
The alkyl polysaccharides surfactants, which are used in conjunction with the aforementioned surfactant have a hydrophobic group containing from about 8 to about 20 carbon atoms, preferably from about 10 to about 16 carbon atoms, most preferably from about 12 to about 14 carbon atoms, and polysaccharide hydrophilic group containing from about 1.5 to about 10, preferably from about 1.5 to about 4, most preferably from about 1.6 to about 2.7 saccharide units (e.g., galactoside, glucoside, fructoside, glucosyl, fructosyl; and/or galactosyl units). Mixtures of saccharide moieties may be used in the alkyl polysaccharide surfactants. The number x indicates the number of saccharide units in a particular alkyl polysaccharide surfactant. For a particular alkyl polysaccharide molecule x can only assume integral values. In any physical sample of alkyl polysaccharide surfactants there will be in general molecules having different x values. The physical sample can be characterized by the average value of x and this average value can assume non-integral values. In this specification the values of x are to be understood to be average values. The hydrophobic group (R) can be attached at the 2-, 3-, or 4- positions rather than at the 1-position, (thus giving e.g. a glucosyl or galactosyl as opposed to a glucoside or galactoside). However, attachment through the 1- position, i.e., glucosides, galactoside, fructosides, etc., is preferred. In the preferred product the additional saccharide units are predominately attached to the previous saccharide unit""s 2-position. Attachment through the 3-, 4-, and 6- positions can also occur. Optionally and less desirably there can be a polyalkoxide chain joining the hydrophobic moiety (R) and the polysaccharide chain. The preferred alkoxide moiety is ethoxide.
Typical hydrophobic groups include alkyl groups, either saturated or unsaturated, branched or unbranched containing from about 8 to about 20, preferably from about 10 to about 18 carbon atoms. Preferably, the alkyl group is a straight chain saturated alkyl group. The alkyl group can contain up to 3 hydroxy groups and/or the polyalkoxide chain can contain up to about 30, preferably less than about 10, alkoxide moieties.
Suitable alkyl polysaccharides are decyl, dodecyl, tetradecyl, pentadecyl, hexadecyl, and octadecyl, di-, tri-, tetra-, penta-, and hexaglucosides, galactosides, lactosides, fructosides, fructosyls, lactosyls, glucosyls and/or galactosyls and mixtures thereof.
The alkyl monosaccharides are relatively less soluble in water than the higher alkyl polysaccharides. When used in admixture with alkyl polysaccharides, the alkyl monosaccharides are solubilized to some extent. The use of alkyl monosaccharides in admixture with alkyl polysaccharides is a preferred mode of carrying out the invention.
Suitable mixtures include coconut alkyl, di-, tri-, tetra-, and pentaglucosides and tallow alkyl tetra-, penta-, and hexaglucosides.
The preferred alkyl polysaccharides are alkyl polyglucosides having the formula
R2O(CnH2nO)r(Z)x
wherein Z is derived from glucose, R is a hydrophobic group selected from the group consisting of alkyl, alkylphenyl, hydroxyalkylphenyl, and mixtures thereof in which said alkyl groups contain from about 10 to about 18, preferably from about 12 to about 14 carbon atoms; n is 2 or 3 preferably 2, r is from 0 to 10, preferable 0; and x is from 1.5 to 8, preferably from 1.5 to 4, most preferably from 1.6 to 2.7. To prepare these compounds a long chain alcohol (R2OH) can be reacted with glucose, in the presence of an acid catalyst to form the desired glucoside. Alternatively the alkyl polyglucosides can be prepared by a two step procedure in which a short chain alcohol (R1OH) can be reacted with glucose, in the presence of an acid catalyst to form the desired glucoside. Alternatively the alkyl polyglucosides can be prepared by a two step procedure in which a short chain alcohol (C1-6) is reacted with glucose or a polyglucoside (x=2 to 4) to yield a short chain alkyl glucoside (x=1 to 4) which can in turn be reacted with a longer chain alcohol (R2OH) to displace the short chain alcohol and obtain the desired alkyl polyglucoside. If this two step procedure is used, the short chain alkylglucosde content of the final alkyl polyglucoside material should be less than 50%, preferably less than 10%, more preferably less than about 5%, most preferably 0% of the alkyl polyglucoside.
The amount of unreacted alcohol (the free fatty alcohol content) in the desired alkyl polysaccharide surfactant is preferably less than about 2%, more preferably less than about 0.5% by weight of the total of the alkyl polysaccharide. For some uses it is desirable to have the alkyl monosaccharide content less than about 10%.
The used herein, xe2x80x9calkyl polysaccharide surfactantxe2x80x9d is intended to represent both the preferred glucose and galactose derived surfactants and the less preferred alkyl polysaccharide surfactants. Throughout this specification, xe2x80x9calkyl polyglucosidexe2x80x9d is used to include alkyl polyglycosides because the stereochemistry of the saccharide moiety is changed during the preparation reaction.
An especially preferred APG glycoside surfactant is APG 625 glycoside manufactured by the Henkel Corporation of Ambler, Pa. APG25 is a nonionic alkyl polyglycoside characterized by the formula:
CnH2n+1O(C6H10O5)xH
wherein n=10 (2%); n=122 (65%); n=14 (21-28%); n=16 (4-8%) and n=(0.5%) and x (degree of polymerization)=1.6. APG 625 has: a pH of 6 to 10 (10% of APG 625 in distilled water); a specific gravity at 25xc2x0 C. of 1.1 g/ml; a density at 25xc2x0 C. of 9.1 lbs/gallon; a calculated HLB of 12.1 and a Brookfield viscosity at 35xc2x0 C., 21 spindle, 5-10 RPM of 3,000 to 7,000 cps.
The proton donating agent which is optionally used at a concentration of 0.1 to 5 wt. % is selected from the group consisting of inorganic acids such as sulfuric acid and hydrochloric acid and hydroxy containing organic acid, preferably a hydroxy aliphatic acid, which are selected from the group consisting of lactic acid or citric acid, orthohydroxy benzoic acid or citric acid or glycolic and mixtures thereof.
In final form, the instant compositions exhibit stability at reduced and increased temperatures. More specifically, such compositions remain clear and stable in the range of 5xc2x0 C. to 50xc2x0 C., especially 10xc2x0 C. to 43xc2x0 C. Such compositions exhibit a pH of 5 to 8. The compositions are readily pourable and exhibit a viscosity in the range of 100 to 1000 milliPascal . second (mPas.) as measured at 25xc2x0 C. with a Brookfield RVT Viscometer. Preferably, the viscosity is maintained in the range of 150 to 600 mPas.